package second.binarytree;


public class Solution12 {
    public boolean isBalanced(TreeNode root) {
        return depth(root) != -1;
    }

    public int depth(TreeNode root) {
        if (root == null) return 0;

        int left = depth(root.left);
        int right = depth(root.right);
        if (left == -1 || right == -1) return -1;

        if (Math.abs(left - right) > 1) return -1;

        return Math.max(left, right) + 1;
    }
}

